Method of and apparatus for treatment of petroleum



J. W. LEWIS.

METHOD OF AND APPARATUS FOR TREATMENT OF PETROLEUM.

APPLICATION FILED APR. 19, 1917. Patented Jan. 4, .1921.

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A 117 Coo/ed Condenaeru J. W. LEWIS.

METHOD OF AND APPARATUS FOR TREATMENT OF PETROLEUM.

APPLICATION FILED APR-19, 1917- I 1,364,443. Patented Jan,- 4, 1921.

b SHEETS-SHEET 2.

Still J. w. LEWIS. A METHOD OF AND APPARATUS FOR TREATMENT OF PETROLEUM.

APPLICATION FILED APR. 19, 1917. v

Patented Jan. 4, 1921.

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Reducing V0] 1/8 '63 v 6170 5 T60 H I ii T If 417 T k S K avwe/wtoz 2 atmnw 1 w. LEWIS.

METHOD OF AND APPARATUS FOR TREATMENT OF PETROLEUM.

APPLICATION FILED APR. 19, 1917.

1,364,443; Patented Jan. 4,1921.

5 SHEETS-SHEET 4.

J. W. LEWIS.

METHOD OF AND APPARATUS FOR TREATMENT OF PETROLEUM.

APPLICATION FILED APR-19.1917.

Patented Jan. 4, 1921.

5 SHEETSSHEET 5.

Men @1 naw EK un EN $3 EN NEW EN ATTO R N EY UNITED STATES PATENT. o r1 1 JOSEPH W. LEWIS, 0F PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO THE ATLAN- H TIC REFINING COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION I OF PENNSYLVANIA.

METHOD or AND APPARATUS FOR 'TREATMENT or PETROLEUM.

Application filed April 19, 1917. sem u To all whom it may concern.

vented certain new and useful Improvements in Methods of and Apparatus for Treatment of Petroleum, of which the following is a specification.

apparatus for treating crude petroleum,

petroleum distillate o-r petroleum residuum,

more particularly for the production of light hydrocarbons such as naphth'asor gasolenes. and burning or kerosene oil;

My invention residesin a method for the treatment of crude petroleum, petroleum distillate or petroleum residuum, as gas oil or fuel oil, or oils lighter or heavier than gas oil or fuel oil, by subjecting the same to high temperature while maintaining' thereon pressure which will more o r less completelyprevent fractional distillation of the oil treated, the applied heat-effecting a destructivedistillation or dissociation or cracking of the heavier oils into naphthas or gasolenes and burning oil of lower boiling points, and in general oils lighter in Specific gravity, these resulting products comprising both saturated hydrocarbons, so-called paraiiins, or those which do not readily react with cold sulfuric'acid of specific gravity -1.85'an'd which do not react. with or absorbv bromin or iodin, and unsaturated hydroca'r-.v

bons, those which have unsatisfied bonds and which readily react with the aforementioned acid and rea'ct with or absorb bromin or iodin, the entire change being efl'e'cted during application of heat under .the aforementionedpressure. The light hydrocarbon productsreadily-distil ofl notwithstanding the pressure thereon, and the vapors of these products, together withsome small amount erably subjected to a preliminary cooling, as in an air cooled condenser, whereby the vapors of the heavier oils are condensed and returned to the treating apparatus, while the Specification of Letters Patent.

; Patented Jan. 4,1921.

such reduced pressure are subjected to the principal cooling operation and condensed pressure stills each provided with a reduc-v .1ng valve for reducing the pressure of the I resultant vapors fromstill pressure to some My invention relates to a method of and with the; result that its rate of firin pres-' sure and rate of production of distillate are controllable independently of the other stills, withthe further result that the yield and character of a desired product or prodnets are controllable, with the result that I the yield of the desired product or products of the wholebattery of stillsmay be' made greater with greater uniformity of the desired product or. products thanthe case where the stills of a battery are in communication witheach other during operation. While the vapors of the" lighter products may be reduced in pressure to substantially atmospheric immediately after the preliminary cooling referred to,-it is preferred to maintain them under suitable pressure during condensation to liquid form, for the purpose of reducing or minimizing the amount of light vapors held inthe permanent gas which is a further pro'ductof the destructive distillation; and it will therefore'be understood that the amount of the pressure maintained upon. the vapors after passage 3 through the reducing valve and before re? lease" to substantially atmospheric pressure 13 independent of the still pressure and produces no chemical effect upon or change in a a-the light hydrocarbon products and serves to of vapors ofthe heavier products, are pref-' strip the gas of light oil vapors. By so operating upon the vapors they retain a greater proportion of the light vapors which otherwise would pass oii. in orwiththe gas.

The light hydrocarbons above refe rre d .to constitute a crude distillate which is then preferably treatedashereinafter described; 1

andgthe' residuum is preferably treated or disposed of as hereinafter described- My. invention resides also in'apparatus for treatmentof petroleum or petroleum distillate or petroleum residuum for carrying outa method of the character above described or for any other suitable purpose.

For an illustration of one of the forms my apparatus may take and forone of the modes of carrying out my process, reference may be had to the accompanying drawings, in which:

Figure 1 is a side elevational'view, partly in section; of pressure still apparatus and some of its adjuncts.

\ F'g. 1 is a fragmentary plan showing connections from still to drum.

f Fig. 2 is a fragmentary sectional view showlng a part of the pressure still structure. I

i Fig. 3 is.a fragmentary view, on enlarged scale, of the air cooled condenser, reducing valve and associated parts.

Fig. 4 is a fragmentary side elevational view, on enlarged scale, of part of the air cmfied condenser and connections with the sti 4 Fig. 5 is a vertical sectional view, some parts in elevation, of "a pressure reducing valve.

- Fig. 6 is a diagrammatic view illustrating a battery of stills and adjuncts and a system -of piping utilizable in' carrying out my 30.

process.

Fig. 7 is a chart illustrative of a mode of treating pressure still roducts.

Referring to Fig. 1, is a vertical .still of boiler plate, provided with the man holes and between and around the upper parts of the tubes 8 and the drum D and pass.

downwardly in contact with the lower parts of the tubes 8' andthe drum D and hence into the flue passages 17, 17, Fig. 2, which communicate With a'stack or chimney, not shown, which may be common to several stills. Communicating with the interior of the chamber containingthe drums and tubes is a stack 18 having the closing cover 19, which latter may be moved to open position to allow escape-of hot gases from the chamber, either in a measure to control the temerature to which the tubes 8 and" drums D, are subjected, or rapidly to cool the chamber at the end of a run. At the upper end of the still S is the vapor outlet pipe 20, Figs. 1 and 4, communicating through valve 21 with the sweat out line or pipe 22, and with the pipe 23 leading to the safety valve 24 whose discharge side'communicates with the vertically extending pipe 25. The

. main vapor line 20 communicates also through the valve 26 with the upwardly and then downwardly extending vapor line or pipe 27 which communicates with the initial. manifold or header 28 communicating with the three transversely extending initial header pipes 29 with which communicate 1,- 1 near its bottom and top. The oil to be treated is pumped into the still through the pipe 2 until it reaches the top of the pipe 3 within the still, which serves to indicate when the proper level-has been reached by overflow through the pipe 3 and its control valve 4, appearance of oil at the outer and lower orifice of the pipe 3 indicating that the proper level is reached, whereupon the valve 4 is closed. 'Within the brickwork structure 5 are disposed the upper and lower cylindrical drums D and D .each connected at its one end by pipes 6 and 7 see Fig. 1?, with the interior of the still 6, the pipes t5 and 7 of each pair connecting to opposite from' to ash removing cars 15. In the cham-- ber containing the drums D, D and the tubes 8 are the bafiles 16, Fig. 2, with the 7 result that the hot gases pass from the firebox or chamber 10 through the opening 9,

the numerous small vertically extending pipes 30 connected in various groups through the top connecting pipes 31 with the numerous small downwardly extending. pipes, 32 communicating with the transverse terminal header pipes 33 which all com-muni: cate with the terminal header or manifold 34. The numerouspipes 30 and 32, and associated connections, are housed within the structure 35 open at its bottom and having at its top an open-work cover 36 .of wire mesh or the like.

These pipes 30, 32 and their connections constitute means for preliminarily cooling the vapors rising from the still S and constitute the preliminary air cooled condenser, the cooling air entering at the bottom of the housing 35 and passing upwardly between the tubes 30, 32 and out through the open cover 36. i

I From transverse header pipes 29 and 33 extend downwardly the several pipes 37 Figs. 1 and 3, which communicate at their lower end with a pipe 38 from which is connected the riser pipe 39 controlled by valve 40 and communicating with the interior ofthe still S at its top, this ,piping structure constituting a runbacklwhereb'y there. are returned into the still S those heavy oils whose vapors have been con- 'densed 1n the air condenser and which have been only partially, if at all, subjected to" the desired treatment. U

While it is preferred to resort to preliminary partial coolingliof the vapors'from the still, as by recourse to an air condenser or its equivalent, my inventionis not limited" thereto and contemplates its omission.

Referring now more particularly to Fig.

' 3, there is connected with the header 34 of the air condenser a pipe-41, to which is connected the tell-tale pipe 42 controlled by valve 43,.communicatin through the valve 44 and the pipe 45 with reducing valve 46 whose outlet communicates through the pipe 47 and the valve 48 with the vapor line or pipe 49. The pipes 41 and 49 are also connected through the normally closed by-pass valve 50.

The pressure-reducing means may be of any suitable type, a, Watson reducing Valve having been found satisfactory in operation.

In Fig. 5 is illustrated such a reducing valve in which the movable valve member 51 is attached to a stem 52 normally forced upwardly by the arm 53 pivoted at 54 and thrust upwardly by the spring 55, On the upper end of the stem 52 in thechamber 56 is the diaphragm 57 whose upper side is subjected to any suitable medium under pressure, as for example, compressed air delivered through the pipe 58 controlled by valve 59 and havingthe throttled outlet 60 to the space above the diaphragm 57. Communicating with the space above the diaphragm 57 is the tube 61 in which is disposed the vertically movable plug valve 62 whose upper end engages the stem 63 connected to the diaphragm 64 whose downwardmovement is opposed by the spring 65. WVith the space above the diaphragm 64 connects the pipe 66, controlled by a) valve 67 and communicating through tlie valve 68, Fig. 3, with the pipe 41; a pressure gage 69, Fig. 3, being connected with'the pipe 66 and showing the pressure upon the air condenser and still.

The air pressure exerts an upward force upon the plug valves 62 in opposition to the downward thrust upon the stem 63 occasioned by the still pressure upon the upper side of the diaphragm 64.

lVhen the still pressure falls below a predetermined value, the spring raises the stem 63, and the air pressure in the space above the diaphragm 57 is to some extent released, the escaping air passing out through the pipe 70. This reduces the pressure on the upper side of the diaphragm 57, allowing the spring 55 to move the valve stem 52 upwardly to move the valve member 51 toward its seat and therefore throttle the passage between the pipes 45 and 47, and so allowing less vapor to escape from the air condenser to the pipe 47; and due to this throttling action of the valve 51, upon subsequent rise in pressure in the still the diaphragm 64 will have greaterpressure ex erted on its upper side with a tendency to move the stem 63" and valve 62 downwardly and throttle the air escape through the the intake of the outlet 70 and thereby increase the pressure on the upper side of the diaphragm 57, with resultant downward movement of the stem 52 and the attached valve'51, thereby moving the latter farther from its seat and allowing freer passage of vapors from pipe 45 to pipe 47. In this way the reducing valve operates continuously to allow the vapors at still pressure to escape and assume in the pipe 47 and parts connected therewith a pressure lower than that in the still or air condenser, and in fact in the pipe 47 73 similarly, cooled by water or other suitable mediu Referring to Fig. 6, three of a battery of stills and associated parts are shown.

Each condensing worm 73 in the sweatout line connects by pipe 74 with the look box 75 which in turn connects through pipe 76 with the common header pipe 77 which delivers into the slop tank 7 8.

And each of the main condensing worms 71 connects by pipe 7 9 with a receivingdrum. 80 carrying at its top a pressure gage 81. From the'bottom of the drum 80 leads a pipe 82 to the meter 83 which is connected by pipe'84 with the pressure-reducing dis-' tillate-delivering trap 85 which delivers through the pipe 86 with the main or header 87 which delivers through the valve 88 to the crude distillate storage tank 89.

From near the top of each drum 80 there is afforded communication through pipe 90 controlled by valve 91 with a reducing valve 92, Which may be of any suitable type, as for example, a .lVatson reducing valve of the character hereinbefore described, which in turn communicates through pipe 93 with the gas main or header 94 delivering to the scrubber or absorber 95 which delivers gas ,through the reducing valve 96 to the gas lower connecting pipes 6 and 7 into the drum D and thence rising through the pipes 8 into and filling the drum D. and its pipes 6 and 7 connecting with the still S.-

The valves 26,40 and 50 are closed. Fire is started in the furnace chamber 10 and the charged oil gradually raised in temperature, the valve 21 in the sweat-out line 22 being open so that no substantial pressure is maintained on the charge in the still, and as the charge rises sufiiciently in temperature the water entrained with the oil will be vaporized into steam and passes oil through the .pipe 20, valve 21, sweat-out line 22, through the condenser coil 73 where it is condensed into water, which passes through pipe 74 to.='

' reducing valve 46 allows escape of vapors from pipe 45 to pipe 49, the valves 44 and 48 being open. The vapors of heavy oils which may pass from the still S: to the air condenser are therein condensed and ,re-

turned to the still through the runback connections 37 and 39 through the now open valve 40.

The lighter vapors of the desired products are not condensedin the air condenser and; pass through'the pipe 49 and through the condensing worm .71, where they are condensed into liquid form and then pass 1 into the drum 80 into which is delivered also through the same line 49 and worin 71.

gas which is formed in the still S and which is 'carried through the air condenser and through the reducing valve 46 and through the condensing worm 71 to the drum 80. The crude distillate in the drum 80 passes through the meter 83 and thence through the trap 85, the system between the reducing valve 46 and the trap 85 being preferably at a pressure intermediate still and atmospheric-pressures. The trap 85 delivers the crude. distillate at lower pressure, substantially atmospheric, through the pipe 86 to the main or header 87, from which it is delivered through valve 88 to the crude distillate storage tank 89.

Simultaneously the gas delivered to the drum 80 through the line 79 is delivered through p1pe'90 and valve 91 to reducing valve 92, which reduces its pressure, as for example, to 25 pounds per square inch, which 1s" sufficient toedeliver it through pipe 93 and header 94 to and through the scrubher or absorber 95, which extracts from it any entrained oil vapors which the pressure and cooling in worm 71 ,did not serve to con- I dense to liquid form, and is delivered through reducing valve 96, which further reduces the pressure toslightly above atmospheric, as for example, three or four inches of water, at which'pressure it is delivered into the gas storage tank 97, 'or otherwise disposed of.

It will be understood that the scrubber 95 may be omitted, in which case there may be omitted also the reducing valve 96, and in such event the reducing valve 92 may be so adjusted as todeliver the gas at suitable pressure for delivery into storage tank 97 g The firing is continued until the oil in the still S has been reduced to a residuum of suitable or desired percentage of the volume of the charge. To determine when this stageis reached the valve 101, Fig. 1, is opened from time to time, and when for the first time vapor is delivered through the same and through the water-cooled coil 102 to the outlet 103, it is lmown that the charge has been sufliciently reduced and has reached a level corresponding with the upper end of the pipe 104 communicating through valve 101 with coil 102.

The fire is then withdrawn, the reducing valve 46 is by-passed by closing valves 44 and 48 and opening valve 50, whereupon the gas and vapor contents of the still will pass therefrom through the air condenser, thence through the valve 50 to the line 49, and whatever vapors pass over will be condensed in the coil 71 and delivered as liquid, together with the gas passing over, into the drum 80,,the.connection between the drum 80 and the reducing valve 92 being closed by valve 91. The valve 99 ,is now opened and the gas escapes gradually through the pipe98'into the main 100 and is delivered directly into the storage tank 97, or is delivered to any gas supply line or other storage tank.

The reducing distillate, that is, the aforementioned condensed vapors passingpver when reducing the pressure on the st ll at the end of a pressure distillation run, 1s de livered from the drum 80 through the valve 9 105 into pipe 106, which by-passes the meter 83 and trap 85, into pi e 86 and .through pipe 87 into tank 89, t e valve 105 being closed during the normal operation of the still; and when reducin the pressure thereon as described, the va ve 108 is closed to prevent reducin distillate flowing from the drum 80 throug the meter and trap.

When the pressure on the still has been mitted as through the pipes 109, 110,111,

within the pipes 8 are also removed by devices imilar to boiler'tube cleaners.

The still is then ready for recharging and 7 operation.

In operation of the battery of stills it is preferred that some are always in operation I while one or more are being discharged,

cleaned and recharged, whereby the s stem iscontinuously producing the desire distillate.

For the purposes of carrying out .my process, fuel oil or gas oil of 33 Be. gravity, or of higher or lower gravity, or any other suitable oil lighter or heavier than gas oil or fuel oil, and with an initial boiling point I at atmospheric pressure of from 350 degrees F. to 550 or 600 degrees F. or higher, is charged'into the still; or crude petroleum may be charged into the still. Heat is applied to the oil under treatment to raise it to a temperature ranging from 650 degrees F. upwardly at the be inning of the run and increasing to 800- egrees F. and upwardly at the end of the run, with resultant destructive distillation, dissociation or cracking of the oil under treatment into saturated and unsaturated hydrocarbons of lower boiling points and gravities, the resultant pressure upon the oil under'treatment ranging from above atmospheric upwardly to300 pounds per square inch gage, or

higher, preventing almost completely fractional distillation of the heavier oil under treatment, which is thereby caused to remain in the still and undergo dissociation or cracking. .The lower boiling point products,"naphtha or gasolene and burning or kerosene oils, and some small amount of the oil under treatment, constitute the crude distillate.

Where alplurality or battery of stills is operated, it is a feature of my invention to maintain the individual stills independent of each other by recourse to pressure-reducing means in association with each still,

whereby intercommunication between the stills 'is prevented.

The independence of the stills is preferably produced by employment of reducing. valves 46 located intermediate the stills and the main condenser worms 71. Or the indefpendence of the stills may be procured when the reducingvalves 46 are omitted by employing as before the traps 85 and the reducing valves 92, in which case they will respectively deliver condensate and gas from substantially still pressure to any lower presworms '71 and drums and pipe 87 may be atmospheric or substantially atmospheric. And where both reducing valves 46 and devices and 96 are employed, as before described, the pressures in the worm 71 and receivers 80 will be intermediate still and 75 And atmospheric pressures, In all these cases,

however, the stills are maintained independ ent of each other in that there is no com-- munication between them. From this structure and mode of operation there results'the advantage that each still is individually controllable and each may be controlled to produce a maximum yield of the desired distillate, with the resultthat the entire battery of stills yields a greater amount of desired distillate than in the case where the stills of the battery are in communication with each other, and therefore all-under the same pressure Where the stills-are main tained independent,each may be fired at such rate, and under such pressure and temperature conditions that the rate-of production of desired distillate is controllable and may be made such as to procure maximum yield of the desired distillate, with the result, as stated, that the yield of the entire battery of stills may so be made a maximum and greater than in the case where the stills of a battery are in communication with each other and therefore all operated at the'same pressure.

Furthermore, where a battery of stills is operated, some are always in operation,

generally at different stages of their runs,

while some arebeing re-charged; and where there is var1at1on ,1n nature or composltion ofthe charging material from time to time,

it 'followsthat difi'ere'nt stills of a battery may be operated upon charges differing more or less from each other and therefore difference of the charges due to their having arrived at different stages of their respective runs, each still may be so operated as to produce the desired distillate andthe .desired yield of such distillate, withthe result that'the yield of the entire battery may be made more uniform as to .character and, as previously stated, greater in quantity,

than in the case where the stills of a battery are in communication with each other.

By employing reducing valve 46 between the still and the condensing worm 71, as

preferred, it is possible to obtain a regulation of still operation more uniform than when the regulating device is located at the outlet of the main condenser, because then still operation is based on changesof con- 85and reducing valve 92, may be madeany thing desired, but is ordinarily pounds gage pressure, though it will be understood that it may be suitably higher, as only slightly less than still pressure, for the purpose of preventing large amounts of the light distillate vapors passing off in the gas.

The crude and reducing distillates, received in the storage tank 89 are operated upon as follows, as will beunderstood from Fig. 7, constitutin one of the modeso carrying out my process, it being understood that my invention is not limited thereto. 7

- The crude distillate'is charged intofire still No. .1 operated at substantially atmospheric pressure, from which there distils over gasolene distillate. The residuum in the lene.

fire still No.1 is delivered into fire still No. 2, which is also operated at substantially atmospheric pressure and from which there passes overhead a distillate comprising gaso-. lene and a small amount of kerosene or burning oil. The overhead distillates from fire stills Nos. 1 and 2 are mixed and then subjected to treatment by concentrated sulfuric acid, the treated distillate being then charged into a steam .still in which thecontents are heated, at atmospheric pressure, b a. steam coil submerged in the still 0 arge. The distillate passing overhead from the steam still comprises motor gaso= The residuum in this steam still is kerosene or burning oil, which is then treated with concentrated sulfuric acid with kerosene or lamp oil as the finished product. If, however, the color of the residuum this steam still is unsatisfactory,

it may be charged back into the fire stills I above mentioned with the crude distillate from thefpressure still? From fire still No. 2 the residuum is. delivered into fire still No. 3, where it is dis tilled at substantially atmospheric pressure,

a chart illustrative of the'distillate passing overhead therefrom comprising lamp oil or kerosene distillate containing some gasolene or naphtha. The residuum offire still No. 3 is delivered into fire still No. 45, where at substantially atmospheric pressure there passes overhead a dis- 'tillate comprising kerosene or lamp oil and 1 some naphtha or gasolene.

Theresiduum in fire still No. 4 is gas oil, which may be delivered to gas oil storage or otherwise disposed of.

These overhead distillates from fire stills Nos. 3 and l'are mixed and charged into a steam still, from which there passes overhead distillate of gasolene and kerosene, which is acid treated and then further subjected to steam distillation, giving a finished gasolene or naphtha, the residua from these two last named steam stills being mixed and thlen acid treated to produce afinished lamp o1 .The tar or residuum, exclusive of the carbon left in the tubes, drums and still, remaining after a run, comprises oil in the nature of gas oil with carbon or heavy carbonaceous material in suspension therein, This may be charged into a batch fire still and run to dryness, leaving a residuum of coke, the overhead distillate being gas oil which is delivered to gas oil storageorotherwise disposed of.

Or in lieu of treatin I residuum in a batch fire still as described, it may be treated with concentrated sulfuric acid to remove the coke-forming materials therein by forming an acid sludge, and the clarified oil may then be vretreated accord- .the pressure stilling to the hereinbefore described pressure still process, or may be otherwise disposed of.

The oil resulting from either the acid treatment or fire distillation of the pressure still residuumcontains in solution parafiin wax which is not completely removed in the usual refinery processes and which has not been completely dissociated or cracked into light oil distillates in the pressure still, it being well known in the oil refining art that such paraifin wax readily cracks or dissociates even at atmospheric pressure intona 'htha, gasolene and kerosene.

Such para n wax as remains in the gas oil after the aforementioned acid treatment or fire still treatment of the pressure still-residuum may then be recovered bythe usual cold pressure or cold settling processes, or otherwiseextracted, with orwithout previous separaon to suitable, degree the residuum has valuable lubricating oil properties. And after removal of wax by the aforementioned cold pressing. process, the oil may 'be fractionclude all the aforementioned oils.

lVhat I claim is:

1. The method of producing lighter oil from heavier petroleum, which consists in subjecting the latter to cracking temperature under pressure exceeding atmospheric pressure, stepping down the pressure of the resultant vapors to a substantially lower pressure intermediate said pressure and atmospheric pressure, condensing said vapors into liquid form while under said intermediate pressure. 1

2. The method of producing lighter oil from heavier petroleum, which consists in subjecting the latter to cracking temperature under pressure'exceedingatmospheric pressure, stepping down the pressure of the.

resultant gas and vapors to a substantially lower pressure intermediate said pressure and atmospheric pressure, cooling said gas and vapors while under said intermediate pressure, separating said gas from the resulting condensate while under said inter mediate pressure, and thereafter separately and independently reducing the pressure on said gas and said condensate.

3. The method of producing lighter oil from heavier petroleum, which consists in subjecting the latter to cracking temperature under pressure exceeding atmospheric pressure, stepping down the pressure of the resultant gas and vapors to a substantially lower pressure intermediate said pressure and atmospheric pressure, separating said gas from the resulting, condensate while under said intermediate pressure, further reducing thepressure of said gas to a pressure substantially above atmospheric, and scrubbing said gas while under said last named pressure.

4. The method of producing lighter oil from heavier petroleum, which consists in subjecting the. latter to cracking temperature under pressure, exceeding atmospheric pressure, reducing the pressure of the. resultant gas and vapors to a pressure intermediinte'rmediate pressure, said intermediate pressure being of a magnitude to cause substantial stripping of said gas of oil vapors, separating said gas from the condensate while under intermediate pressure, and thereafter scrubbing the gas.

, gas to a pressure substantially above atmos- 5. The method of producing lighter oil I from heavier petroleum, which consists in' subjecting the latter to cracking temperature under pressure exceeding atmospheric pressure, reducing the pressure of the resultant gas and vapors to a pressure intermediate said pressure and atmospheric presj sure, cooling said gas and vapors While under said intermediate pressure, said intermediate pressure being of a magnitude to cause substantial stripping of said gas of oil vapors, separating said gas from the condensate while under intermediate pressure, further reducing the pressure of said pheric and scrubbing the same, and thereafter further reducing the pressure of said gas.

6. The methodof producing lighter oil from heavier petroleum, which consists in subjecting the latter to cracking temperature-under pressure exceeding atmospheric pressure,removing from the residuum unsaturated hydrocarbons,

and thereafterv again subjecting -said residuum to dissociat-[BO ing or cracking temperature under pressure, whereby lighter oil is produced.

7. The. method of producing lighter oil from heavier petroleum containing wax,

which consists in subjecting said petroleum and the contained ax to cracking temperature under pressure greater than atmospheric, whereby the heavier oil and wax are dissociated into lighter hydrocarbons, removing from the resultant residuum tarry matter, and thereafter subjecting the clarified residuum to a cracking tempera-ture under pressure in excess of atmospheric pressure. v

8. The method, of producing wax and lighter oil from heavier petroleum containing wax, which consists in subjecting said petroleum and the contained wax to cracking temperatureunder pressure greater than atmospheric, whereby the heavier oil and wax are dissociated into lighter hydrocan bons, treating the resultant residuum to re-' move therefrom color imparting reaction" products, and thereafter extracting wax remaining in theclarified solution.

9. The method of producing wax and lighter oil from heavier petroleum containing wax, which consists in subjecting said petroleum and the contained wax to. cracking temperature under-pressure greater than atmospheric, whereby'the heavieroil and wax are dissociated into lighterl hydrocarbons, acid treating the resultant residuum, and thereafter removing from said acid treated residuum wax remaining in solution therein.

10. The method of producing wax and the contained wax to cracking temperature 55 under pressure above atmospheric pressure.

under pressure greater than atmospheric,

' whereby the heavier oil and wax are dissociated into lighter hydrocarbons; acid treat ing the resultant residuum, thereafter removing from said acid treated residuum Wax remainingin' solution therein, and reducing said residuum after removal of wax by fractional distillation, leaving a residuum: having lubricating oil properties.

11. The method of producing lighter oil from heavier petroleum,.which consists in subjecting the latter to cracking temperature under pressure exceeding atmospheric pressure, preliminarily cooling the resultant vapors to cause condensation of heavy" vapors without condensation of the vapors of the lighter desired products and returnpors without condensation of the vaporsof the lighter desired products and returning the heavy' condensate to the petroleumun'der treatment, thereafter stepping down the pressure of the remaining vapors to a substantially lower pressure intermediate said pressure and atmospheric pressure, and

while under said intermediate pressure'condensing them. j

13. Themethod of producing lighter oil from heavier petroleum, which consists in subjecting the latter to cracking temperature under pressure exceeding atmospheric pressure, preliminarily cooling the resultant .vapors to' cause condensation of heavy vapors without condensation of "the vapors of theflighter desired products, returning the preliminary condensate to the still, thereafter stepping down the pressure of the vapors of the lighter desired products to substantially lower pressure and while under such reduced pressure condensing them, and

. from heavier petroleum, which consists in separating gas and scrubbing the same while 14. The method of producing lighter oil subjecting the latter to cracking temperature underpressure exceeding atmospheric pressure, preliminarily cooling. the resultant vapors to cause condensation of--heavy,v a-

pors without condensation of the ofv the lighter desired prOducts'return ng the preliminary condensate 'to' the still,""therepressure, and separating gas while substantially ower pressure intermediate as" of the lighter desiredproductsa still and'atmospheric pressures, condensing said vapors while under said intermediate under said intermedlate pressure.

cracking temperature under pressure exceeding atmospheric pressure, stepping down the pressureof the resultant gas and vapors to a pressure substantially lower than still pressure and substantially above, atmospheric pressure, cooling. said gas and vapors while under said last named pressure, and upon completion of a run gradually reducing the pressure upon the charge to substantially atmospheric pressure by redissociation leasing the vapors of the products "and of the-oil'under treatment, and

l5.- The method of treating petroleum, which consists in subjecting the same to condensing said vapors to form a reducing distillate.

16. The method of treating petroleum, which consists in subjecting the same to cracking temperature under pressure exceeding atmospheric pressure, stepping-down the pressure of the resultant gas and vapors to a pressure substantially lower than still pressure and substantially above atmospheric pressure, cooling said gas and vapors while under said last named pressure, and

ing the pressure upon the charge to substantially atmospheric pressure by releasing the vapors of the dissociation'products and of the, oil under treatment, condensing said vapors to form a reducing distillate, and

upon-completion of a run gradually reduc- I thereafter fractionally distilling said redu' e- I ing distillate.

17. The method of producing lighter oil from heavier petroleum, which consists in simultaneously and continuously subjecting a plurality of charges of the latter of submingling the condensates/to constitute a composite crude distillate.

18. The method of producing llghteroil from heavier petroleum, which consists in simultaneously subjecting a plurality -of charges of the latter of substantially similar compositions at different stages of treatment independently of each other to cracking temperatures under pressures exceeding atmospheric pressure, independently con densing the. resultant vapors, and commin- 'gling the. condensates to constitute a coin- .posite crude distillate. 1

- 19. The method 'fproduding lighter-"e115 from heavier petroleum, which consists in" after stepping down the pressure of the vasimultaneously subjecting .a' plurality. of

charges of the latter of substantially similar compositions independently of each other to cracking temperatures under pressures exceeding atmospheric pressure, independently condensing the vapors resultant from said charges at pressures substantially below still and substantially above atmospheric pressures, releasing the condensates and commingling them to constitute a composite crude distillate.

20. Petroleum treating apparatus comprising a pressure still, a fire chamber eX- ternal thereto for heating the oil therein to cracking temperature, a preliminary condenser, a vapor connection between said still and said preliminary condenser, a main.condenser, an automatic pressure reducing valve between said condensers for delivering to said main condenser oil vapors at a superatmospheric pressure substantially below the pressure in said preliminary condenser, and

means for maintaining said super-atmospheric pressure in said main condenser.

21. Petroleum treating apparatus comprising a pressure still, a condenser in which vapors are condensed under pressure, an

automatic trap delivering the condensate tolower pressure and preventing escape of gas, and automatic means for "separately reducing the pressure of the gas.

22. Petroleum treating apparatus comprising a pressure still, a preliminary condenser, a vapor connection between said still andpreliminary condenser, a main condenser, an automatic pressure reducing valve delivering oil vapors to said main condenser at a super-atmospheric pressure substan-.

tially below the pressure in said preliminary condenser, and condensate-deliverlng pres sure reducing means maintaining said superatmospheric pressure in said main condenser and delivering condensate therefrom at lower ressure.

23. etroleum treating apparatus comprising a pressure still, a preliminary condenser, a vapor connection between said still and said condenser, amain condenser, agpressure reducing valve between said condensers for maintaining in said main condenser a pressure substantially below the pressure in said preliminary condenser and substantially above atmospheric pressure, a receiver receiving gas and condensate from said mainv condenser, a gas connection leading from said receiver, and a pressure reducing valve in said gas connection.

24. Petroleum treating apparatus comprising a pressure still, a preliminar condenser, a vapor connection between sald still and said condenser, a main condenser, a

pressure reducing valve between said condensers for maintaining in said main condenser a pressure substantially below the pressure in saidpreliminary condenser and substantially above atmospheric pressure, a

' receiver-receiving gasand condensate from said main condenser, a gas connection leading from said receiver, a pressure reducing :valve in said connection, a scrubber to which gas is delivered through said connection, and a reducing Valve through which gas is delivered from said scrubber.

' 25. Petroleum treating apparatus comprising a pressure still, a preliminary condenser, a vapor connection between said still and said condenser, a 'main condenser, a;

denser, a vapor connection between said still and said condenser, a main condenser, a reducing, valve between said condensers, and a valve for by-passing said reducing valve. 1

27. Petroleum treating apparatus comprising a pressure still, a fire chamber for heating. the oil therein to cracking temperature, a preliminary condenser, a vapor connection I between said still and said condenser, a main condenser, a pressure. reducing valve between said condensers for main taining in said main condenser a pressure substantially below the pressure of said preliminary condenser and substantially above atmosphericpressure, a runback from said preliminary condenser to said still, and means deliveringcondensate from said main condenser to a region at a pressure lower than existing in said main condenser.

28. Petroleum treating apparatus comprising a pressure still, a preliminary condenser comprising initial and terminal headers, a plurality of tubes connecting said headers, runback connections from said headers to said still, a main condenser, and a pressure reducing valve between a terminal header of said preliminary condenser and said main condenser for maintaining in said main condenser a pressure'substantially below the pressure in said preliminary condenser and substantially above atmospheric pressure.

29. Petroleum treating apparatus comprising a battery of pressure stills, a condenser for each still in which vapors from said still are condensed under pressure, each still and condenser being independent of the other stills and condensers, a pressure-reducing connection between each still and its condenser for efiecting in said condenser a pressure substantially below said pressure and and condenser being independent of the 10 substantially above atmospheric pressure, a other stills and condensers, distillate-receiupipe receiving condensate fromv all said coning means, and fluid-delivering pressure-redensers, and a pressure-reducing connection 'ducing means between each of said con- 5 between each of said condensers and sai densers and said receiving means. pipe. In testimony whereof I have hereunto 15 30. Petroleum treating apparatus comaflixed my signature this 27 day of March, prising a battery of pressure stills, a con- 1917.

denser associated with each still, each still 7 J OSEPH W. LEWIS. 

